Effects of drought stress and rehydration on physiological and biochemical of four oak species in China
Abstract Background: Quercus fabri Hance, Quercus serrata Thunb, Quercus acutissima Carruth, and Quercus variabilis BL are four Chinese oak species commonly used for forestation. In recent years, with the global warming caused by the greenhouse effect, seedlings in mountainous areas after afforestation often suffer seasonal drought stress, which seriously affects their survival and growth. In order to ensure the survival of seedlings, we need to select oak species with strong drought resistance. Therefore, we first need to understand the differences in drought resistance of the four oak tree species at the seedling stage, and comprehensively evaluate their drought resistance capabilities by studying the changes in the physiological and biochemical characteristics of the seedlings under continuous drought and rehydration conditions.Methods: The four oak seedlings were divided into drought-rewatering treatment group and normal watering control group. For the seedlings of the drought-rewatering treatment group, drought stress lasting 31 days was used, and then re-watering and recovering for 5 days. The water parameters, osmotic adjustment substance content, antioxidant enzyme activity and photosynthesis parameters of the seedlings in the two groups were measured every 5 days. Principal component analysis, correlation analysis and membership function were used to analyze the physiological and biochemical characteristics of the seedlings of the four oak in two groups.Results and conclusions: Compared with the control group, the relative water content, water potential, net photosynthetic rate, transpiration rate, and stomatal conductance levels of the four oaks all showed a downward trend under continuous drought stress, and showed an upward trend after rehydration. The soluble protein, soluble sugar, proline, peroxidase, superoxide dismutase and catalase content of the four oaks increased first and then decreased under drought stress, and then increased after rehydration. The content of glycine betaine and malondialdehyde continued to increase, and gradually decreased after rehydration. The weight of each index was calculated by PCA, and then the comprehensive evaluation of each index was carried out through the membership function method. The drought resistance levels of the four oak species were as follows: Q. serrata > Q. fabri > Q. variabilis > Q. acutissima.
